The worldwide economic value of pollination services provided by insects in 2005 was estimated to be $190 billion for the main crops that feed the world. The volume of production of pollinator dependent crops has increased by 300% over the last five decades, making livelihoods increasingly dependent on the provision of pollination. Wild pollinators have declined in occurrence and diversity in northwestern Europe and North America. However, other sources note declines in other parts of the world. More than three quarters of the leading types of global food crops rely to some extent on pollination for yield and/or quality. Pollinator dependent crops contribute to 35% of global crop production volume.